py/formatfloat: Fix exact int formatting on 32-bit mingw.

dlech · dlech · commit 38e455aaabcf · 2022-12-18T22:43:14.000-06:00
When compiler optimizations are enabled on the mingw version of gcc, we
are getting failing tests because of rounding issues, for example:

    print(float("1e24"))

would print

    9.999999999999999e+23

instead of

    1e+24

It turns out special compiler options are needed to get GCC to use the
SSE instruction set instead of the 387 coprocessor.

This also lets us re-enable other failing tests.

Signed-off-by: David Lechner &lt;david@pybricks.com&gt;
diff --git a/ports/windows/Makefile b/ports/windows/Makefile
@@ -84,14 +84,17 @@ ifneq ($(FROZEN_MANIFEST),)
 CFLAGS += -DMICROPY_QSTR_EXTRA_POOL=mp_qstr_frozen_const_pool -DMICROPY_MODULE_FROZEN_MPY=1 -DMPZ_DIG_SIZE=16
 endif
 
+ifeq ($(shell $(CC) -dumpmachine),i686-w64-mingw32)
+# https://lemire.me/blog/2020/06/26/gcc-not-nearest
+CFLAGS += -msse -mfpmath=sse -march=pentium4
+endif
+
 CXXFLAGS += $(filter-out -std=gnu99,$(CFLAGS))
 
 include $(TOP)/py/mkrules.mk
 
 .PHONY: test test_full
 
-RUN_TESTS_SKIP += -e math_fun -e float2int_double -e float_parse -e math_domain_special
-
 test: $(BUILD)/$(PROG) $(TOP)/tests/run-tests.py
 	$(eval DIRNAME=ports/$(notdir $(CURDIR)))
 	cd $(TOP)/tests && MICROPY_MICROPYTHON=../$(DIRNAME)/$(BUILD)/$(PROG) $(PYTHON) ./run-tests.py $(RUN_TESTS_SKIP)
